specific Gravity , and comparative Wear of Gold. 47 
GOLD ALLOYED WITH ARSENIC. 
Experiment 1. 
Eleven ounces one pennyweight and three grains ( = 5307 
grs.) of gold, 23 carats 3jgrs. fine, being completely melted, 
eighteen pennyweights and twenty-one grains ( = 453g rs 0 of 
pure metallic arsenic were added, and the whole being rapidly 
stirred, was quickly poured into a greased mould of iron. 
The bar was of the colour of fine gold, and, although brittle, 
yet it bent in some measure before it broke. It weighed eleven 
ounces one pennyweight and nine grains; so that, of 18 dts. 
21 grs. of arsenic, only six grains remained in combination with 
the gold; consequently, i8dts. 15 grs. had been volatilized. 
Experiment 11. 
As the fine gold, in the foregoing experiment, retained so very 
small a portion of the arsenic, it appeared possible that copper 
might assist to fix that volatile substance. 
To eighteen pennyweights and ten grains of the fine gold in 
fusion, nineteen grains of pure copper were added, being half 
the weight of the standard proportion of alloy. 
When the copper was perfectly melted, and, by stirring, had 
been well incorporated with the gold, the crucible was removed, 
and at that moment nineteen grains of arsenic were added, and 
being quickly stirred, the metal was immediately poured into a 
mould. 
The time which elapsed from the raising of the crucible 
to the pouring of the metal, was rather less than one minute ; 
but, upon weighing the ingot, it appeared that the whole of 
the 19 grains of arsenic had been volatilized ; and this was 
